Flow switch algorithm for pulser driver

Abstract

A pulser driver assembly of a measurement-while-drilling tool that includes an improved flow switch is disclosed. The flow switch uses multiple accelerometers of different types that measure acceleration changes in a system. The accelerometer data is then filtered and processed by an onboard microcontroller. The filtered data is then passed to a fuzzy logic voting algorithm which systematically and robustly characterizes the signal, and identifies the flow state.

The invention claimed is: 
     
       1. A measurement while drilling tool comprising:
 a flow switch circuit comprising:
 a plurality of accelerometers configured to detect, respectively, flow values of fluid flow and output the flow values; and 
 a microprocessor configured to input the flow values from the plurality of accelerometers and identify a fluid flow state, 
 
 wherein the measurement while drilling tool initiates fluid flow processes after the microprocessor identifies a predetermined fluid flow state. 
 
     
     
       2. The measurement while drilling tool of  claim 1 , wherein the flow switch circuit further comprises one or more memory elements to store flow data. 
     
     
       3. The measurement while drilling tool of  claim 1 , wherein the plurality of accelerometers comprise at least one low-g analog accelerometer. 
     
     
       4. The measurement while drilling tool of  claim 1 , wherein the plurality of accelerometers comprise at least one high-g analog accelerometer. 
     
     
       5. The measurement while drilling tool of  claim 1 , wherein the plurality of accelerometers comprise at least one digital accelerometer. 
     
     
       6. The measurement while drilling tool of  claim 1 , further comprising a main valve to generate pressure pulses. 
     
     
       7. The measurement while drilling tool of  claim 6 , wherein the main valve stops generating pressure pulses when the microprocessor identifies a different predetermined fluid flow state. 
     
     
       8. The measurement while drilling tool of  claim 1 , wherein the microprocessor is further configured to confirm a fluid flow state change after identifying a consistent fluid flow state over a threshold period of time. 
     
     
       9. The measurement while drilling tool of  claim 1 , wherein the microprocessor is further configured to confirm a fluid flow state change after identifying a consistent fluid flow state over a threshold count. 
     
     
       10. The measurement while drilling tool of  claim 6 , further comprising input/output ports communicatively coupled with a gamma ray detector, wherein the microprocessor is further configured to receive and encode gamma ray data from the gamma ray detector through the input/output ports, and wherein the main valve is configured to generate pulses to transmit encoded gamma ray data after the microprocessor identifies a predetermined fluid flow state. 
     
     
       11. The measurement while drilling tool of  claim 6 , further comprising input/output ports communicatively coupled with an orientation module, wherein the microprocessor is further configured to receive and encode orientation data from the orientation module through the input/output ports, and wherein the main valve is configured to generate pulses to transmit encoded orientation data after the microprocessor identifies a predetermined fluid flow state. 
     
     
       12. The measurement while drilling tool of  claim 1 , wherein the microprocessor is further configured to identify a failed accelerometer and identify the fluid flow state without the flow values from the failed accelerometer.